Self-contained underwater breathing apparatus (scuba) is used to describe any diving set that allows the diver to carry the breathing gas supply with him or her. There are several claims to its invention, based on old drawings. The first workable form probably dates from the early nineteenth century. There is a brief report of an American engineer, Charles Condert, who made a scuba in which the compressed air was stored in a copper pipe worn around his body. The gas was released into a hood that covered the upper half of his body. Accumulation of carbon dioxide was controlled by allowing the respired gas to escape through a small hole. It was then replaced by fresh gas from the storage pipe. Condert died while diving with his equipment in the East River in New York in 1831.
In 1838, Dr Manuel Guillaumet filed a patent in France for a back-mounted, twin-hose demand regulator that was supplied with air from hoses to the surface. A patent for a similar device was also filed in England earlier that year by William Newton, but it seems likely that this was done on behalf of Guillaumet.
Another early development was the Rouquayrol and Denayrouze device of 1865 (Figure 1.3). This set was supplied with air from the surface that was breathed on demand via a mouthpiece. It was fitted with a compressed air reservoir so that the diver could detach himself or herself from the air hose for a few minutes. The endurance, as a scuba, was limited by the amount of air in the reservoir.
The first successful scuba with an air supply appears to have been developed and patented in 1918 by Ohgushi, who was Japanese. His system could be operated with a supply of air from the surface or as a scuba with an air supply cylinder carried on the back. The diver controlled the air supply by triggering air flow into the mask with the diver’s teeth. Another scuba was devised by Le Prieur in 1933. In this set, the diver carried a compressed air bottle on the chest and released air into the face mask by opening a tap.
In 1943, Cousteau and Gagnan developed the first popular scuba as we know it today. It was an adaptation of a reducing valve that Gagnan had evaluated for use in gas-powered cars and was far smaller than the Rouquayrol-Denayrouze device.
Closed-circuit oxygen sets were developed during the same period as the modern scuba. In these rebreathing sets, the diver is supplied with oxygen and the carbon dioxide is removed by absorbent. These sets are often called scuba, but they may be considered separately because of the difference in principles involved. The patent for the first known prototype of an oxygen rebreather was given to Pierre Sicard, who was French, in 1849. The first known successful rebreathing set was designed by English engineer H. A. Fleuss in 1878. This was an oxygen set in which carbon dioxide was absorbed by rope soaked in caustic potash.
Because of the absence of lines and hoses from the diver to the surface, the set was used in flooded mines and tunnels where the extra mobility, compared with the standard rig, was needed. Great risks were taken with this set and its successors when used underwater because the work of Paul Bert on oxygen toxicity was not widely known. This equipment was the precursor of oxygen sets used in clandestine operations in both world wars and of other sets used in submarine escape, firefighting and mine rescue.